A New Design Of Fault Indicator Based On The CC430MCU

The fault indicator is an important tool for the power sector to find the line faults of electrical grid. The characteristics of its low cost, flexible and easy to install, handling without power cut, and the combination of the short-circuit detection and the ground fault detection function in many current products, make this product more convenient for users to find the short-circuit and grounding faults. Therefore, the fault indicator is very popular in the market. However, the accuracy rate of fault detection and the system power consumption have been the main problems of fault indicator.This paper presents a new design of fault indicator based on the CC430MCU system. The indicator can accurately indicate the fault type and the fault location correctly. It sends fault message to the monitor center of electrical grid wirelessly through wireless communication module to facilitate the control of the network. The introduction of CC430microcontroller simplified the hardware design of control system. Coupled with the ultra-low power feature of MCU, the entire control system can run in the ultra-low power model when electrical grid running normally. The program selected a single-chip which integrates with CC1101RF module. It saved the design costs and increased system integration. For the accuracy rate problem of fault detection, the paper chooses a group of more reasonable fault indication criterion. Based on the wavelet transform and the Fourier transform, the paper proposed an improved method for extracting grid current harmonic amplitude, two-stage method. Two-stage method divided the harmonic amplitude of the extraction process into two stages. First stage, use the wavelet transform to divest the non-steady state component from the sample signal. Second stage, use the windowed Fourier transform to extract the harmonic amplitude. It is verified by the simulation that the proposed method is more accurate and proper to analyze harmonics in the electric power system than the wavelet transform and the windowed Fourier transform.The new indicator has merits of small size, light weight, clear alarm, long useful time, low cost, free maintenance and the function of "telesignalization".